The present invention relates to a method and apparatus for processing data received by a GPS receiving device which outputs data indicating the location of a vehicle at present according to the Global Positioning System (hereinafter referred to as GPS).
A navigation system has been recently studied and developed for a vehicle which lends the vehicle to a predetermined destination. The system is provided with a display unit displaying map information prerecorded in a memory. The location where the vehicle is at present is pointed out on the display unit.
Such a system requires a detecting device, such as the abovedescribed GPS or the like, for detecting the place where the vehicle is at present. The detecting device receives radio waves radiated from a number of artificial satellites, at its highest accuracy, and can detect the present location of where the vehicle within 20 meters.
The detecting precision of the system is influenced by the position of the artificial satellites, various perturbations of the satellites, the condition of the ionosphere, and the like. Therefore, the desired detecting precision may not be obtained by using original data from the satellites as directly received by the GPS receiving device. Further, since the location where the moving vehicle is at present changes at every moment, it is desirable for the receiving device to detect more precisely the present place of the vehicle taking into account the continuous changes in the vehicle's position.